[css-round-display] Update a device-radius property2 (2 values -> 1 value)

Author: hyojinLGE

css-round-display/Overview.bs

@@ -67,7 +67,7 @@ By the mechanism of media queries, if the value of the 'device-radius' media fea
 Note: To define a '<code>range</code>' type media feature, the feature may be written as a normal media feature, but with a '<code>min-</code>' or '<code>max-</code>' prefix on the feature name. '<code>min-</code>' or '<code>max-</code>' prefixes express 'greater or equal to' or 'smaller or equal to' constriants respectively.
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 <p>
-The length or percentage value of the '<code>device-radius</code>' property define the radius of a quarter ellipse in terms of the shape of the corner of the outer screen edge (This is similar to the '<code>border-radius</code>' properties. see the 'border-radius' description). If the length is zero, the shape of screen is a rectangle, otherwise that is a rectangle with round corners or a regular circle. A percentage value of the '<code>device-radius</code>' is proportional to the diameter of the screen. If the screen shape is a regular circle, '<code>device-radius</code>': 50% has a true value, because a half of the diameter of the regular circle is the radius of the screen shape. An negative value is not allowed.
+The length or percentage value of the '<code>device-radius</code>' property defines a radius of a quarter ellipse in terms of the shape of the corner of the outer screen edge (This is similar to the '<code>border-radius</code>' properties. see the 'border-radius' description). If the length is zero the shape of screen is a rectangle, otherwise it is a rectangle with rounded corners or a regular circle. A percentage value of the '<code>device-radius</code>' is proportional to the diameter of the screen. If the screen shape is the regular circle, '<code>device-radius</code>': 50% has a true value, because a half of the diameter of the regular circle is the radius of the screen shape. An negative value is not allowed.
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 <div class='example'>